As the United States ramps up its rhetoric on trade toward China and continues sanctions on Russia, the two former cold warriors are coming together for the largest Russian military exercise since 1981, Vostok- 2018. The exercise is set to include over 300,000 Russian troops, 36,000 vehicles and over 1,000 aircraft.

This cooperation is just the latest sign that the two former adversaries are willing to bury the hatchet in the face of the threats to both of the nation’s strategic interests. In recent years Moscow once again began selling its latest and greatest military equipment to China after over a decade of pause caused by issues around intellectual property.

These sales have drastically improved the capabilities of the Chinese armed forces in many key areas where they were previously lagging behind the West. The Russian S-400 Triumph air defence system for example, gives the Chinese the ability to effectively deny enemy aircraft access to airspace within a 400km radius.

If Russian claims about its effectiveness prove to be accurate, it also has the ability to “see through” the stealth abilities of U.S aircraft like the B-2 Spirit bomber, F-22 Raptor and the F-35 strike fighter.

This is a potentially nightmare scenario for Pentagon defence planners, a prospective fight with the Chinese armed forces over the South China Sea for example just became that much harder.

The delivery of these, potentially game changing weapons are just one part of the warming relationship between Beijing and Moscow. The Chinese participation in the Vostok-2018 exercises is a huge change compared when they were last held in 2010. Back in 2010 the exercise was conducted with China being considered the potential foe according to geopolitics analysts.

At Vostok-2018 things could scarcely be more different, the Chinese armed forces will now line up side by side with the Russians, a profound change in the relationship between Beijing and Moscow in a relatively short period of time.

What has happened to bring about this change?

Both Russia and China are facing American led attempts to curtail their potential or existing spheres of influence.

For the Russians it was the coup against the Russian friendly government in Kiev of Viktor Yanukovych, which was backed partially by the United States. For decades the United States had been breaking a promise made in 1990 for NATO not to expand into Eastern Europe.

With the removal of the effective buffer state between the bulk of NATO forces and Russia’s borders the Kremlin burst into action. The Russians quickly seized the Crimean peninsula and quickly began arming separatists in the Eastern part of Ukraine.

For China it’s the expansion of their sphere of influence that is causing the problems. China believes it owns almost the entirety of the South China Sea with its “9-dash line” claim.

This has unsurprisingly raised serious flags with not only the countries who believe their territory is being encroached on, but also those who rely on the South China Sea for martime trade.

As China continues its meteoric rise there is a strong belief among certain officials in Beijing that war with the United States is “inevitable”. This belief coupled with the United States “Pivot to Asia” has only further inflamed tensions between Washington and Beijing.

So where are relations heading between Moscow and Beijing now?

An alliance between Beijing and Moscow may still be a long while off, but the recent rounds of cooperation between the two former adversaries on everything from military exercises to trade agreements leads credence to its potential.

Different geopolitical analysts paint either Moscow or Beijing as the reticent partner in any potential alliance. Russia is allegedly seen by the Chinese a potential liability given its involvement in existing conflicts in Ukraine and its position as the far inferior economic party in any alliance.

China is apparently viewed by Russian military officials as a potential unreliable partner. China’s military may be extremely powerful on paper but it is a nation that has not been tested in a real war in decades.

The once unthinkable alliance between Beijing and Moscow may not end up happening, but the very possiblity is none the less the stuff of nightmares for Western military planners.